1. Technical Field
The present invention relates to computer networks and more particularly to a method and system for providing Systems Network Architecture (SNA) Access to Telnet 3270 (TN3270) and Telnet 3270 Enhanced (TN3270E) services over Wide Area Networks based on technologies such as Frame Relay (FR), Asynchronous Transfer Mode (ATM), Switched Multimegabit Data Services (SMDS) or Integrated Services Digital Network (ISDN).
2. Description of the Related Art
Every day, for all sorts of reasons, more and more companies are focusing on the consolidation of the multiple specialized networks they directly operate or lease from service providers onto a single protocol network. These multiple specialized networks are based on diverse networking technologies such as Systems Network Architecture (SNA), Internet Protocol (IP) or Internetwork Packet Exchange (IPX). These companies are making the consolidation one of their top priorities, and they are almost exclusively selecting IP (the Internet Protocol) as their protocol of choice. However, for the overwhelming majority of these companies that are using SNA protocols and applications, there still is and will be for the many years to come, a major requirement for employees to keep the capability they always had to have access to the huge amount of existing corporate data residing in traditional mainframes and accessible through SNA applications.
TN3270 and TN3270 Enhanced
In an IP environment, a widely used technique for the transport of SNA information across IP networks is the use of Telnet technologies (TN3270 and TN3270 Enhanced). This technique for SNA green screen workstation users is a Client/Server approach. Host On Demand from IBM or WebClient from CISCO are examples of Client software implementations. Network Utility from IBM or CISCO router's offerings are typical Server implementations (hardware and software).
The TN3270 Client usually runs within the customer's workstation while the Server is usually placed in front of the customer's Data Center mainframes (or sometimes directly within the mainframe itself) or within the customer branch offices. As illustrated in FIG. 1, IP protocols 102 are used between the Server 100 and the Clients 101, while traditional SNA protocols 103 are used between the Server 100 and the target Applications 104 within the mainframe. More information concerning Telnet, TN3270, TN3270 Enhanced, Network Utility and more generally SNA over IP can be found in the following publications incorporated herewith by reference:
IBM 2216/Network Utility Host Channel Connection, Erol Lengerli, Jacinta Carbonell, Thomas Grueter; IBM International Technical Support Organization, January 1999, SG24-5303-00.
IBM Network Utility Description and Configuration Scenarios, Tim Kearby, Peter Gayek, Gallus Schlegel, Imre Szabo, Zhi-Yong Zhang; IBM International Technical Support Organization, January 1999, SG24-5289-00.
Internetworking with TCP/IP—Volume I—Principles, Protocols, and Architecture Douglas E. Comer, Second Edition, Prentice Hall 1991.
SNA and TCP/IP Integration, Jerzy Buczak, Karl Wozabal, Antonio Luca Castrichella, Heikki Lehikoinen, Maria Cristina Madureira, Tsutomu Masaoka, IBM International Technical Support Organization, April 1999, SG24-5291-00.
TCP/IP Tutorial and Technical Overview, Martin W. Murhammer, Orcun Atakan, Stefan Bretz, Larry R. Pugh, Kazunari Suzuki, David H. Wood, IBM International Technical Support Organization, October 1998, GG24-3376-05.
Request For Comments (RFCs) from the Internet Engineering Task Force (IETF):
RFC 1576: TN3270 Current Practices,
RFC 1646: TN3270 Extensions for LU name and Printer Selection,
RFC 1647: TN3270 Enhancements,
RFC 2355: TN3270 Enhancements.
Wide Area Networks
Data transmission with a specific focus on applications is now evolving by integrating a fundamental shift in the customer traffic profile. Driven by the growth of the number of intelligent (programmable) workstations, the pervasive use of local area network (LAN) interconnections, the distributed processing capabilities between workstations and super computers, the new applications and the integration of various and often conflicting structures (e.g., hierarchical versus peer to peer, wide versus local area networks, voice versus data), the data profile consumes more bandwidth and requires more connectivity. The data profile is also bursting and non-deterministic. Based on the above observations, there is a strong requirement for supporting distributed computing applications across high speed wide-area networks that can carry local area network communications, voice and data traffic (and sometimes also even video) among channel-attached hosts, business or engineering workstations, terminals, and small to large file server systems.
The vision of a high speed multi-protocol network is the driver for the emergence of fast packet or cell switching network architectures such as Frame Relay, Asynchronous Transfer Mode or Switched Multimegabit Data Services in which data, voice, or, even in some cases, video information is digitally encoded, chopped into small packets and transmitted through a common set of nodes and links. With the continuously evolving environment, there still is and will be for the many years to come, a major requirement for transporting legacy data traffic, such as System Network Architecture (SNA) traffic across Wide Area Networks.
More information about Wide Area Networks and more particularly about Frame Relay (FR), Asynchronous Transfer Mode (ATM) or Switched Multimegabit Data Services (SMDS) technologies can be found in the following publications incorporated herewith by reference:
High Speed Networking Technology: An Introductory Survey, IBM International Technical Support Organization, July 1995, GG24-3816-02; and
Asynchronous Transfer Mode (Broadband ISDN)- Technical Overview, IBM International Technical Support Organization, June 1994, GG24-4330-00.
An efficient transport of mixed traffic streams on very high speed lines means that for these new network architectures, a set of strict requirements in terms of performance and resource consumption is needed. The set of requirements includes a very high throughput and a very short packet or cell processing time, an efficient set of flow and congestion control mechanisms, and a very large flexibility to support a wide range of connectivity options.